This invention relates to coupling devices, and in particular relates to coupling devices of the quick assembly and disassembly type. Coupling devices in general have had wide spread use for a variety of purposes; but, as will be described, the device of the present invention has particular application for marine purposes in joining lines to sail members or as part of a towing bridle or tow line for disabled craft. Quick connect and disconnect couplings of the general type are well known as evidenced by the devices illustrated in U.S. Pat. No. 458,881 and No. 592,733; and, although such devices were found to be adequate for coupling elements together which were under tension, these prior known devices did tend to accidentally disengage when the lines to which the coupling elements were connected were relaxed. Hence the only useful application of the prior known devices required the maintaining of sufficient tension on the coupling lines so as to prevent the disengagement of the coupling elements.